Database private document sharing

ABSTRACT

An example operation may include one or more of generating, by a first blockchain client, a transaction to a blockchain network to transfer a document, transferring over a private channel, by a second blockchain client, a first key to the first blockchain client, the private channel providing a point-to-point connection between the first and second blockchain clients, encrypting the document using a shared key, transferring, by the first blockchain client, the encrypted document over the private channel, generating, by the second blockchain client, a transaction to acknowledge receipt of the encrypted document, and transferring the shared key encrypted with the first key.

TECHNICAL FIELD

This application generally relates to non-repudiable document sharingfor blockchain networks, and more particularly, to database privatedocument sharing.

BACKGROUND

A centralized database stores and maintains data in a single database(e.g., a database server) at one location. This location is often acentral computer, for example, a desktop central processing unit (CPU),a server CPU, or a mainframe computer. Information stored on acentralized database is typically accessible from multiple differentpoints. Multiple users or client workstations can work simultaneously onthe centralized database, for example, based on a client/serverconfiguration. A centralized database is easy to manage, maintain, andcontrol, especially for purposes of security because of its singlelocation. Within a centralized database, data redundancy is minimized asa single storing place of all data also implies that a given set of dataonly has one primary record.

However, a centralized database suffers from significant drawbacks. Forexample, a centralized database has a single point of failure. Inparticular, if there are no fault-tolerance considerations and ahardware failure occurs (for example a hardware, firmware, and/or asoftware failure), all data within the database is lost and work of allusers is interrupted. In addition, centralized databases are highlydependent on network connectivity. As a result, the slower theconnection, the amount of time needed for each database access isincreased. Another drawback is the occurrence of bottlenecks when acentralized database experiences high traffic due to a single location.Furthermore, a centralized database provides limited access to databecause only one copy of the data is maintained by the database. As aresult, multiple devices cannot access the same piece of data at thesame time without creating significant problems or risk overwritingstored data. Furthermore, because a database storage system has minimalto no data redundancy, data that is unexpectedly lost is very difficultto retrieve other than through manual operation from back-up storage. Assuch, what is needed is a solution that overcomes these drawbacks andlimitations.

SUMMARY

One example embodiment provides a system that includes a blockchainnetwork, comprising one or more of a plurality of blockchain nodes orpeers, configured to endorse, order, and commit blockchain transactions,a first blockchain client, configured to perform one or more of generatea transaction to the blockchain network to transfer a document, encryptthe document using a shared key, transfer the encrypted document over aprivate channel, and transfer the shared key encrypted with the firstkey, and a second blockchain client, coupled to the first blockchainclient by the private channel, configured to perform one or more oftransfer a first key to the first blockchain client using the privatechannel, and generate a transaction to acknowledge receipt of theencrypted document.

Another example embodiment provides a method that includes one or moreof generating, by a first blockchain client, a transaction to ablockchain network to transfer a document, transferring over a privatechannel, by a second blockchain client, a first key to the firstblockchain client, the private channel providing a point-to-pointconnection between the first and second blockchain clients, encryptingthe document using a shared key, transferring, by the first blockchainclient, the encrypted document over the private channel, generating, bythe second blockchain client, a transaction to acknowledge receipt ofthe encrypted document, and transferring the shared key encrypted withthe first key.

A further example embodiment provides a non-transitory computer readablemedium comprising instructions, that when read by a processor, cause theprocessor to perform one or more of generating, by a first blockchainclient, a transaction to a blockchain network to transfer a document,transferring over a private channel, by a second blockchain client, afirst key to the first blockchain client, the private channel providinga point-to-point connection between the first and second blockchainclients, encrypting the document using a shared key, transferring, bythe first blockchain client, the encrypted document over the privatechannel, generating, by the second blockchain client, a transaction toacknowledge receipt of the encrypted document, and transferring theshared key encrypted with the first key.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a block diagram of a document sharing systemincluding a database, according to example embodiments.

FIG. 2A illustrates an example blockchain architecture configuration,according to example embodiments.

FIG. 2B illustrates a blockchain transactional flow, according toexample embodiments.

FIG. 3A illustrates a permissioned network, according to exampleembodiments.

FIG. 3B illustrates another permissioned network, according to exampleembodiments.

FIG. 4 illustrates a system messaging diagram for performing documentsharing, according to example embodiments.

FIG. 5A illustrates a flow diagram of an example method of sharingdocuments in a blockchain, according to example embodiments.

FIG. 5B illustrates a flow diagram of an example method of sharingdocuments among users, according to example embodiments.

FIG. 6A illustrates an example system configured to perform one or moreoperations described herein, according to example embodiments.

FIG. 6B illustrates another example system configured to perform one ormore operations described herein, according to example embodiments.

FIG. 6C illustrates a further example system configured to utilize asmart contract, according to example embodiments.

FIG. 6D illustrates yet another example system configured to utilize ablockchain, according to example embodiments.

FIG. 7A illustrates a process for a new block being added to adistributed ledger, according to example embodiments.

FIG. 7B illustrates contents of a new data block, according to exampleembodiments.

FIG. 7C illustrates a blockchain for digital content, according toexample embodiments.

FIG. 7D illustrates a block which may represent the structure of blocksin the blockchain, according to example embodiments.

FIG. 8 illustrates an example system that supports one or more of theexample embodiments.

DETAILED DESCRIPTION

It will be readily understood that the instant components, as generallydescribed and illustrated in the figures herein, may be arranged anddesigned in a wide variety of different configurations. Thus, thefollowing detailed description of the embodiments of at least one of amethod, apparatus, non-transitory computer readable medium and system,as represented in the attached figures, is not intended to limit thescope of the application as claimed but is merely representative ofselected embodiments.

The instant features, structures, or characteristics as describedthroughout this specification may be combined or removed in any suitablemanner in one or more embodiments. For example, the usage of the phrases“example embodiments”, “some embodiments”, or other similar language,throughout this specification refers to the fact that a particularfeature, structure, or characteristic described in connection with theembodiment may be included in at least one embodiment. Thus, appearancesof the phrases “example embodiments”, “in some embodiments”, “in otherembodiments”, or other similar language, throughout this specificationdo not necessarily all refer to the same group of embodiments, and thedescribed features, structures, or characteristics may be combined orremoved in any suitable manner in one or more embodiments.

In addition, while the term “message” may have been used in thedescription of embodiments, the application may be applied to many typesof networks and data. Furthermore, while certain types of connections,messages, and signaling may be depicted in exemplary embodiments, theapplication is not limited to a certain type of connection, message, andsignaling.

Example embodiments provide methods, systems, components, non-transitorycomputer readable media, devices, and/or networks, which providedatabase private document sharing.

In one embodiment the application utilizes a decentralized database(such as a blockchain) that is a distributed storage system, whichincludes multiple nodes that communicate with each other. Thedecentralized database includes an append-only immutable data structureresembling a distributed ledger capable of maintaining records betweenmutually untrusted parties. The untrusted parties are referred to hereinas peers or peer nodes. Each peer maintains a copy of the databaserecords and no single peer can modify the database records without aconsensus being reached among the distributed peers. For example, thepeers may execute a consensus protocol to validate blockchain storagetransactions, group the storage transactions into blocks, and build ahash chain over the blocks. This process forms the ledger by orderingthe storage transactions, as is necessary, for consistency. In variousembodiments, a permissioned and/or a permissionless blockchain can beused. In a public or permission-less blockchain, anyone can participatewithout a specific identity. Public blockchains often involve nativecryptocurrency and use consensus based on various protocols such asProof of Work (PoW). On the other hand, a permissioned blockchaindatabase provides secure interactions among a group of entities whichshare a common goal but which do not fully trust one another, such asbusinesses that exchange funds, goods, information, and the like.

This application can utilize a blockchain that operates arbitrary,programmable logic, tailored to a decentralized storage scheme andreferred to as “smart contracts” or “chaincodes.” In some cases,specialized chaincodes may exist for management functions and parameterswhich are referred to as system chaincode. The application can furtherutilize smart contracts that are trusted distributed applications whichleverage tamper-proof properties of the blockchain database and anunderlying agreement between nodes, which is referred to as anendorsement or endorsement policy. Blockchain transactions associatedwith this application can be “endorsed” before being committed to theblockchain while transactions, which are not endorsed, are disregarded.An endorsement policy allows chaincode to specify endorsers for atransaction in the form of a set of peer nodes that are necessary forendorsement. When a client sends the transaction to the peers specifiedin the endorsement policy, the transaction is executed to validate thetransaction. After validation, the transactions enter an ordering phasein which a consensus protocol is used to produce an ordered sequence ofendorsed transactions grouped into blocks.

This application can utilize nodes that are the communication entitiesof the blockchain system. A “node” may perform a logical function in thesense that multiple nodes of different types can run on the samephysical server. Nodes are grouped in trust domains and are associatedwith logical entities that control them in various ways. Nodes mayinclude different types, such as a client or submitting-client nodewhich submits a transaction-invocation to an endorser (e.g., peer), andbroadcasts transaction-proposals to an ordering service (e.g., orderingnode). Another type of node is a peer node which can receive clientsubmitted transactions, commit the transactions and maintain a state anda copy of the ledger of blockchain transactions. Peers can also have therole of an endorser, although it is not a requirement. Anordering-service-node or orderer is a node running the communicationservice for all nodes, and which implements a delivery guarantee, suchas a broadcast to each of the peer nodes in the system when committingtransactions and modifying a world state of the blockchain, which isanother name for the initial blockchain transaction which normallyincludes control and setup information.

This application can utilize a ledger that is a sequenced,tamper-resistant record of all state transitions of a blockchain. Statetransitions may result from chaincode invocations (i.e., transactions)submitted by participating parties (e.g., client nodes, ordering nodes,endorser nodes, peer nodes, etc.). Each participating party (such as apeer node) can maintain a copy of the ledger. A transaction may resultin a set of asset key-value pairs being committed to the ledger as oneor more operands, such as creates, updates, deletes, and the like. Theledger includes a blockchain (also referred to as a chain) which is usedto store an immutable, sequenced record in blocks. The ledger alsoincludes a state database which maintains a current state of theblockchain.

This application can utilize a chain that is a transaction log which isstructured as hash-linked blocks, and each block contains a sequence ofN transactions where N is equal to or greater than one. The block headerincludes a hash of the block's transactions, as well as a hash of theprior block's header. In this way, all transactions on the ledger may besequenced and cryptographically linked together. Accordingly, it is notpossible to tamper with the ledger data without breaking the hash links.A hash of a most recently added blockchain block represents everytransaction on the chain that has come before it, making it possible toensure that all peer nodes are in a consistent and trusted state. Thechain may be stored on a peer node file system (i.e., local, attachedstorage, cloud, etc.), efficiently supporting the append-only nature ofthe blockchain workload.

The current state of the immutable ledger represents the latest valuesfor all keys that are included in the chain transaction log. Since thecurrent state represents the latest key values known to a channel, it issometimes referred to as a world state. Chaincode invocations executetransactions against the current state data of the ledger. To make thesechaincode interactions efficient, the latest values of the keys may bestored in a state database. The state database may be simply an indexedview into the chain's transaction log, it can therefore be regeneratedfrom the chain at any time. The state database may automatically berecovered (or generated if needed) upon peer node startup, and beforetransactions are accepted.

In the field of document sharing, there are several problems orpotential problems that must be addressed. First, record keepingmethodologies for sensitive data transaction are not strong. Second,current methods to record a sensitive data handover/transaction may bevulnerable to loss or change. Third, it may be relatively easy to changetransaction records. Fourth, centralized systems to keep track ofrecords may not provide a strong way to verify trust by external partiesinvolved. Fifth, sensitive data is best to keep it from publiceyes—while adding access control can help manage access, there may be alikelihood of unauthorized access. In such cases, it may be best to notexpose the sensitive document to people without a “need to know”.Finally, it may be difficult for external parties to verify trust whenthere are disputes among involving parties.

Some benefits of the instant solutions described and depicted hereininclude improved verification and trust, provides strong evidence thatmay be used for dispute resolution, and provides protocols to transferdocuments and maintain an immutable record to exchange sensitivedocuments through private messaging channels with assurance ofnon-repudiation. Blockchain technology provides inherent structures andoperation that provide non-repudiation to record transactions.

While a traditional database can be used to record all actions taken byvarious parties and software agents related to document sharing, atraditional database has vulnerability in terms of centralizeddata/record storage. This makes it unfit to implement a non-repudiable &verifiable way of recording secure document transfer. By usingblockchain technology, a record made on the blockchain cannot bereversed as blockchain is de-centralized by nature. Blockchaintechnology also removes a scenario of any third parties verifyingtransactions in case of a dispute.

The present application does not describe a functional improvement tocomputer functionality using the disclosed protocols. The disclosedprotocols utilize blockchain technology in order to enable two partiesto share sensitive document information through verifiable transactions,while not exposing sensitive information to a blockchain.

The present application stores the following information in aper-customer immutable ledger provisioned by the disaster recoveryprovider. This information includes, but is not limited to,sender/receiver meta information (i.e., metadata), a hash value of anencrypted document that is being sent, and a hash value of an encryptedkey of a receiving blockchain client.

FIG. 1 illustrates a block diagram of a document sharing systemincluding a database, in according to example embodiments. Referring toFIG. 1, the network 100 includes a first blockchain client 104A, asecond blockchain client 104B, and one or more blockchain nodes or peers108. Although two blockchain clients 104 are shown, identified asblockchain clients 104A and 104B, it should be understood that anynumber of blockchain clients 104 may be present in a blockchain network100—which may be either a public or permissioned blockchain network 100.

In the illustrated embodiment, the first blockchain client 104A is theprovider of a document 116, and the second blockchain client 104B is therecipient of the document 116. The first blockchain client 104A andsecond blockchain client 104B may have a shared or public encryption key124. The second blockchain client 104B also has a first key 120associated with the second blockchain client 104B. In one embodiment,the first key 120 is a private key associated with the second blockchainclient 104B. In another embodiment, the first key 120 is a shared keyassociated with both the first blockchain client 104A and the secondblockchain client 104B.

In addition to the blockchain network 100, blockchain clients 104A, 104Bare connected by a private channel 112, which is a point-to-pointprivate communication path between blockchain client 104A and blockchainclient 104B. In one embodiment, the private channel 112 is a virtualprivate network (VPN) connection between the blockchain clients 104A,104B. In another embodiment, the private channel 112 may be acommunication path using cloud storage the present application disclosescommunication protocols for document sharing that uses a combination ofblockchain transactions and communications over the private channel 112.

Blockchain network 100 may include any number of blockchain nodes orpeers 108, which are shown as blockchain node or peer 108A throughblockchain node or peer 108N. Blockchain nodes or peers 108 perform allfunctions to establish and maintain the blockchain network 100 andprocess blockchain transactions. These functions include, but are notlimited to endorsing transactions, ordering transactions, committingtransactions, and so forth. Each blockchain node or peer 108 includes acopy of a shared ledger 128, which provides immutable storage for allblocks containing blockchain transactions. Blockchain node or peer 108Aincludes shared ledger 128A and blockchain node or peer 108N includesshared ledger 128N.

The first blockchain client 104A begins the process by submitting adocument transfer transaction 132 over the blockchain network 100 to theblockchain nodes or peers 108. The document transfer transaction 132specifies the first and second blockchain clients 132 and may identifythe document 116 but does not reveal the document 116 contents. Thesecond blockchain client 104B then provides the first encryption key 136to the first blockchain client 104A. The first blockchain client 104Aencrypts the document 116 using the shared key 124, and transmits theencrypted document 140 to the second blockchain client 104B over theprivate channel 112. In lieu of a shared key 124, in other embodiments apublic key may be used to encrypt the document 116.

In response to receiving the encrypted document 140, the secondblockchain client 104B generates an acknowledgment transaction 144through the blockchain network 100 to the blockchain nodes or peers 108.The acknowledgment transaction 144 provides acknowledgment that thesecond blockchain client 104B has received the encrypted document 140from the first blockchain client 104A, and includes a hash of thedocument 116 encrypted with the shared or public key 124.

In response to receiving the acknowledgment transaction 144, the firstblockchain client 104A generates an encrypted key transaction 152through the blockchain network 100 to the blockchain nodes or peers 108.The encrypted key transaction 152 provides the shared or public key 124encrypted with the first key 120. The first key 120 was previouslyprovided to the first blockchain client 104A as the first encryption key136 through the private channel 112.

In an alternate embodiment, instead of the first blockchain client 104Agenerates an encrypted key transaction 152 through the blockchainnetwork 100 to the blockchain nodes or peers 108, the first blockchainclient 104A encrypts the shared or public key 124 with the firstencryption key 136 and transfers the encrypted key 148 to the secondblockchain client 148 over the private channel 112. In response, thesecond blockchain client 104B optionally generates a secondacknowledgment transaction 144 through the blockchain network 100 to theblockchain nodes or peers 108. The second acknowledgment transaction 144provides acknowledgment that the second blockchain client 104B hasreceived the encrypted encryption key 124 from the first blockchainclient 104A, and includes a hash of the encryption key 124 encryptedwith the first key 136.

FIG. 2A illustrates a blockchain architecture configuration 200,according to example embodiments. Referring to FIG. 2A, the blockchainarchitecture 200 may include certain blockchain elements, for example, agroup of blockchain nodes 202. The blockchain nodes 202 may include oneor more nodes 204-210 (these four nodes are depicted by example only).These nodes participate in a number of activities, such as blockchaintransaction addition and validation process (consensus). One or more ofthe blockchain nodes 204-210 may endorse transactions based onendorsement policy and may provide an ordering service for allblockchain nodes in the architecture 200. A blockchain node may initiatea blockchain authentication and seek to write to a blockchain immutableledger stored in blockchain layer 216, a copy of which may also bestored on the underpinning physical infrastructure 214. The blockchainconfiguration may include one or more applications 224 which are linkedto application programming interfaces (APIs) 222 to access and executestored program/application code 220 (e.g., chaincode, smart contracts,etc.) which can be created according to a customized configurationsought by participants and can maintain their own state, control theirown assets, and receive external information. This can be deployed as atransaction and installed, via appending to the distributed ledger, onall blockchain nodes 204-210.

The blockchain base or platform 212 may include various layers ofblockchain data, services (e.g., cryptographic trust services, virtualexecution environment, etc.), and underpinning physical computerinfrastructure that may be used to receive and store new transactionsand provide access to auditors which are seeking to access data entries.The blockchain layer 216 may expose an interface that provides access tothe virtual execution environment necessary to process the program codeand engage the physical infrastructure 214. Cryptographic trust services218 may be used to verify transactions such as asset exchangetransactions and keep information private.

The blockchain architecture configuration of FIG. 2A may process andexecute program/application code 220 via one or more interfaces exposed,and services provided, by blockchain platform 212. The code 220 maycontrol blockchain assets. For example, the code 220 can store andtransfer data, and may be executed by nodes 204-210 in the form of asmart contract and associated chaincode with conditions or other codeelements subject to its execution. As a non-limiting example, smartcontracts may be created to execute reminders, updates, and/or othernotifications subject to the changes, updates, etc. The smart contractscan themselves be used to identify rules associated with authorizationand access requirements and usage of the ledger. For example, theinformation 226 may include a first encryption key that may be processedby one or more processing entities (e.g., virtual machines) included inthe blockchain layer 216. The result 228 may include an encrypteddocument. The physical infrastructure 214 may be utilized to retrieveany of the data or information described herein.

A smart contract may be created via a high-level application andprogramming language, and then written to a block in the blockchain. Thesmart contract may include executable code which is registered, stored,and/or replicated with a blockchain (e.g., distributed network ofblockchain peers). A transaction is an execution of the smart contractcode which can be performed in response to conditions associated withthe smart contract being satisfied. The executing of the smart contractmay trigger a trusted modification(s) to a state of a digital blockchainledger. The modification(s) to the blockchain ledger caused by the smartcontract execution may be automatically replicated throughout thedistributed network of blockchain peers through one or more consensusprotocols.

The smart contract may write data to the blockchain in the format ofkey-value pairs. Furthermore, the smart contract code can read thevalues stored in a blockchain and use them in application operations.The smart contract code can write the output of various logic operationsinto the blockchain. The code may be used to create a temporary datastructure in a virtual machine or other computing platform. Data writtento the blockchain can be public and/or can be encrypted and maintainedas private. The temporary data that is used/generated by the smartcontract is held in memory by the supplied execution environment, thendeleted once the data needed for the blockchain is identified.

A chaincode may include the code interpretation of a smart contract,with additional features. As described herein, the chaincode may beprogram code deployed on a computing network, where it is executed andvalidated by chain validators together during a consensus process. Thechaincode receives a hash and retrieves from the blockchain a hashassociated with the data template created by use of a previously storedfeature extractor. If the hashes of the hash identifier and the hashcreated from the stored identifier template data match, then thechaincode sends an authorization key to the requested service. Thechaincode may write to the blockchain data associated with thecryptographic details.

FIG. 2B illustrates an example of a blockchain transactional flow 250between nodes of the blockchain in accordance with an exampleembodiment. Referring to FIG. 2B, the transaction flow may include atransaction proposal 291 sent by an application client node 260 to anendorsing peer node 281. The endorsing peer 281 may verify the clientsignature and execute a chaincode function to initiate the transaction.The output may include the chaincode results, a set of key/valueversions that were read in the chaincode (read set), and the set ofkeys/values that were written in chaincode (write set). The proposalresponse 292 is sent back to the client 260 along with an endorsementsignature, if approved. The client 260 assembles the endorsements into atransaction payload 293 and broadcasts it to an ordering service node284. The ordering service node 284 then delivers ordered transactions asblocks to all peers 281-283 on a channel. Before committal to theblockchain, each peer 281-283 may validate the transaction. For example,the peers may check the endorsement policy to ensure that the correctallotment of the specified peers have signed the results andauthenticated the signatures against the transaction payload 293.

Referring again to FIG. 2B, the client node 260 initiates thetransaction 291 by constructing and sending a request to the peer node281, which is an endorser. The client 260 may include an applicationleveraging a supported software development kit (SDK), which utilizes anavailable API to generate a transaction proposal. The proposal is arequest to invoke a chaincode function so that data can be read and/orwritten to the ledger (i.e., write new key value pairs for the assets).The SDK may serve as a shim to package the transaction proposal into aproperly architected format (e.g., protocol buffer over a remoteprocedure call (RPC)) and take the client's cryptographic credentials toproduce a unique signature for the transaction proposal.

In response, the endorsing peer node 281 may verify (a) that thetransaction proposal is well formed, (b) the transaction has not beensubmitted already in the past (replay-attack protection), (c) thesignature is valid, and (d) that the submitter (client 260, in theexample) is properly authorized to perform the proposed operation onthat channel. The endorsing peer node 281 may take the transactionproposal inputs as arguments to the invoked chaincode function. Thechaincode is then executed against a current state database to producetransaction results including a response value, read set, and write set.However, no updates are made to the ledger at this point. In 292, theset of values, along with the endorsing peer node's 281 signature ispassed back as a proposal response 292 to the SDK of the client 260which parses the payload for the application to consume.

In response, the application of the client 260 inspects/verifies theendorsing peers signatures and compares the proposal responses todetermine if the proposal response is the same. If the chaincode onlyqueried the ledger, the application would inspect the query response andwould typically not submit the transaction to the ordering node service284. If the client application intends to submit the transaction to theordering node service 284 to update the ledger, the applicationdetermines if the specified endorsement policy has been fulfilled beforesubmitting (i.e., did all peer nodes necessary for the transactionendorse the transaction). Here, the client may include only one ofmultiple parties to the transaction. In this case, each client may havetheir own endorsing node, and each endorsing node will need to endorsethe transaction. The architecture is such that even if an applicationselects not to inspect responses or otherwise forwards an unendorsedtransaction, the endorsement policy will still be enforced by peers andupheld at the commit validation phase.

After successful inspection, in step 293 the client 260 assemblesendorsements into a transaction and broadcasts the transaction proposaland response within a transaction message to the ordering node 284. Thetransaction may contain the read/write sets, the endorsing peerssignatures and a channel ID. The ordering node 284 does not need toinspect the entire content of a transaction in order to perform itsoperation, instead the ordering node 284 may simply receive transactionsfrom all channels in the network, order them chronologically by channel,and create blocks of transactions per channel.

The blocks of the transaction are delivered from the ordering node 284to all peer nodes 281-283 on the channel. The transactions 294 withinthe block are validated to ensure any endorsement policy is fulfilledand to ensure that there have been no changes to ledger state for readset variables since the read set was generated by the transactionexecution. Transactions in the block are tagged as being valid orinvalid. Furthermore, in step 295 each peer node 281-283 appends theblock to the channel's chain, and for each valid transaction the writesets are committed to current state database. An event is emitted, tonotify the client application that the transaction (invocation) has beenimmutably appended to the chain, as well as to notify whether thetransaction was validated or invalidated.

FIG. 3A illustrates an example of a permissioned blockchain network 300,which features a distributed, decentralized peer-to-peer architecture.In this example, a blockchain user 302 may initiate a transaction to thepermissioned blockchain 304. In this example, the transaction can be adeploy, invoke, or query, and may be issued through a client-sideapplication leveraging an SDK, directly through an API, etc. Networksmay provide access to a regulator 306, such as an auditor. A blockchainnetwork operator 308 manages member permissions, such as enrolling theregulator 306 as an “auditor” and the blockchain user 302 as a “client”.An auditor could be restricted only to querying the ledger whereas aclient could be authorized to deploy, invoke, and query certain types ofchaincode.

A blockchain developer 310 can write chaincode and client-sideapplications. The blockchain developer 310 can deploy chaincode directlyto the network through an interface. To include credentials from atraditional data source 312 in chaincode, the developer 310 could use anout-of-band connection to access the data. In this example, theblockchain user 302 connects to the permissioned blockchain 304 througha peer node 314. Before proceeding with any transactions, the peer node314 retrieves the user's enrollment and transaction certificates from acertificate authority 316, which manages user roles and permissions. Insome cases, blockchain users must possess these digital certificates inorder to transact on the permissioned blockchain 304. Meanwhile, a userattempting to utilize chaincode may be required to verify theircredentials on the traditional data source 312. To confirm the user'sauthorization, chaincode can use an out-of-band connection to this datathrough a traditional processing platform 318.

FIG. 3B illustrates another example of a permissioned blockchain network320, which features a distributed, decentralized peer-to-peerarchitecture. In this example, a blockchain user 322 may submit atransaction to the permissioned blockchain 324. In this example, thetransaction can be a deploy, invoke, or query, and may be issued througha client-side application leveraging an SDK, directly through an API,etc. Networks may provide access to a regulator 326, such as an auditor.A blockchain network operator 328 manages member permissions, such asenrolling the regulator 326 as an “auditor” and the blockchain user 322as a “client”. An auditor could be restricted only to querying theledger whereas a client could be authorized to deploy, invoke, and querycertain types of chaincode.

A blockchain developer 330 writes chaincode and client-sideapplications. The blockchain developer 330 can deploy chaincode directlyto the network through an interface. To include credentials from atraditional data source 332 in chaincode, the developer 330 could use anout-of-band connection to access the data. In this example, theblockchain user 322 connects to the network through a peer node 334.Before proceeding with any transactions, the peer node 334 retrieves theuser's enrollment and transaction certificates from the certificateauthority 336. In some cases, blockchain users must possess thesedigital certificates in order to transact on the permissioned blockchain324. Meanwhile, a user attempting to utilize chaincode may be requiredto verify their credentials on the traditional data source 332. Toconfirm the user's authorization, chaincode can use an out-of-bandconnection to this data through a traditional processing platform 338.

FIG. 4 illustrates a system messaging diagram for performing documentsharing, according to example embodiments. Referring to FIG. 4, thesystem messaging diagram 400 includes a sending blockchain client 410, areceiving blockchain client 420, and a blockchain network 430.

The sending blockchain client 410 creates a transaction proposal 415 topropose to send a document to the receiving blockchain client 420, andprovides the document transfer transaction proposal 416 to theblockchain network 430. The blockchain network 430 endorses thetransaction proposal 425 and provides the endorsed transaction 426 tothe sending blockchain client 410 and the receiving blockchain client420.

The receiving blockchain client 420 obtains a first encryption key 435that is associated with the receiving blockchain client 420, andtransfers the first encryption key 436 to the sending blockchain client410 over a private channel between the sending blockchain client 410 andthe receiving blockchain client 420. The sending blockchain client 410,after receiving the first encryption key 436, encrypts a documentrelated to the document transfer transaction 416 with a secondencryption key 440. The encrypted document 441 is provided to thereceiving blockchain client 420 over the private channel. The secondencryption key, while typically a shared key, may instead be a publicencryption key. Additionally, an additional sharing channel may be usedin lieu of a private channel, such as cloud storage.

The receiving blockchain client 420 next calculates a hash of theencrypted document 441, and in response generates an acknowledgmenttransaction 446 to the blockchain network 430. The blockchain network430 endorses the transaction 450 and provides the endorsed transaction451 to the sending blockchain client 410 and the receiving blockchainclient 420.

The sending blockchain client 410 then encrypts the second encryptionkey with the first encryption key 455. In a first embodiment, thesending blockchain client 410 transfers the encrypted key 456 to thereceiving blockchain client 420 over the private channel. In response,the receiving blockchain client 420 generates a second acknowledgmenttransaction (not shown) to the blockchain network 430. In a secondembodiment, the sending blockchain client 410 generates an encrypted keytransaction 457, which includes the encrypted key, to the blockchainnetwork 430. The blockchain network 430 endorses the transaction 460 andprovides the endorsed transaction 461 to the sending blockchain client410 and the receiving blockchain client 420.

FIG. 5A illustrates a flow diagram 500 of an example method of sharingdocuments in a blockchain, according to example embodiments. Referringto FIG. 5A, the method 500 may include one or more of the followingsteps.

At block 504, a blockchain transaction proposal is created to transfer adocument. The blockchain transaction proposal specifies a documentsender and a document receiver. One or more endorser nodes or peersendorse the transaction proposal and return endorsements.

At block 508, the document receiver transfers a first key to thedocument sender over a private communication link between the documentsender and the document receiver. The first key corresponds to and isassociated with the document receiver.

At block 512, the document sender encrypts the document using a sharedkey in possession of both the document sender and the document receiver,or a private key.

At block 516, the document sender transfers the encrypted document tothe document receiver over the private communications link or channel.

At block 520, the document receiver generates a blockchain transactionproviding an acknowledgment of receiving the document and hash. The hashis of the document encrypted with the shared or private key.

At block 524, the document sender generates a blockchain transaction toprovide the shared or private key encrypted by the first key. Alltransactions are stored in immutable blocks in a shared ledger of theblockchain network.

FIG. 5B illustrates a flow diagram of an example method 550 of sharingdocuments among users, according to example embodiments. Referring toFIG. 5B, the method 550 may include one or more of the following steps.

At block 554, a request to share the document is obtained. The documentsharing application obtains a request to share a document from a user ofthe enterprise. In some embodiments, the user may not be associated withan enterprise or an organization, but may rather simply be associatedwith a particular user account within the computing environment.

At block 558, a document layout is extracted. The document sharingapplication can extract the document layout associated with a documentfile.

At block 562, a document structure is extracted. The document sharingapplication can extract the document structure associated with thedocument file.

At block 566, a sharing destination is identified. The document sharingapplication can identify a destination with which the document isshared. In some embodiments, the destination can comprise an emailaddress. In other embodiments, the destination may comprise another formof user identifier with which a user to whom the document is shared canbe identified.

At block 570, a document representation with security restrictions isgenerated. The document sharing application can generate a documentrepresentation associated with the document based upon the documentlayout and the document structure. A document representation can includea security restrictions that restricts use of a portion of the documentassociated with the document representation of the document.

At block 574, a reference is transmitted to a destination. The documentsharing application can transmit a reference to the documentrepresentation, such as a hyperlink, to the destination associated withthe request to share the document. In some embodiments, the documentsharing application need not generate a new document representation witheach request to share a particular document. In some embodiments' thedocument sharing application may generate a document representationassociated with a document when a user creates a particular document orinitiates storage of a document in the data store and create a referenceto the document representation upon receiving a request to share thedocument with another user.

FIG. 6A illustrates an example system 600 that includes a physicalinfrastructure 610 configured to perform various operations according toexample embodiments. Referring to FIG. 6A, the physical infrastructure610 includes a module 612 and a module 614. The module 614 includes ablockchain 620 and a smart contract 630 (which may reside on theblockchain 620), that may execute any of the operational steps 608 (inmodule 612) included in any of the example embodiments. Thesteps/operations 608 may include one or more of the embodimentsdescribed or depicted and may represent output or written informationthat is written or read from one or more smart contracts 630 and/orblockchains 620. The physical infrastructure 610, the module 612, andthe module 614 may include one or more computers, servers, processors,memories, and/or wireless communication devices. Further, the module 612and the module 614 may be a same module.

FIG. 6B illustrates another example system 640 configured to performvarious operations according to example embodiments. Referring to FIG.6B, the system 640 includes a module 612 and a module 614. The module614 includes a blockchain 620 and a smart contract 630 (which may resideon the blockchain 620), that may execute any of the operational steps608 (in module 612) included in any of the example embodiments. Thesteps/operations 608 may include one or more of the embodimentsdescribed or depicted and may represent output or written informationthat is written or read from one or more smart contracts 630 and/orblockchains 620. The physical infrastructure 610, the module 612, andthe module 614 may include one or more computers, servers, processors,memories, and/or wireless communication devices. Further, the module 612and the module 614 may be a same module.

FIG. 6C illustrates an example system configured to utilize a smartcontract configuration among contracting parties and a mediating serverconfigured to enforce the smart contract terms on the blockchainaccording to example embodiments. Referring to FIG. 6C, theconfiguration 650 may represent a communication session, an assettransfer session or a process or procedure that is driven by a smartcontract 630 which explicitly identifies one or more user devices 652and/or 656. The execution, operations and results of the smart contractexecution may be managed by a server 654. Content of the smart contract630 may require digital signatures by one or more of the entities 652and 656 which are parties to the smart contract transaction. The resultsof the smart contract execution may be written to a blockchain 620 as ablockchain transaction. The smart contract 630 resides on the blockchain620 which may reside on one or more computers, servers, processors,memories, and/or wireless communication devices.

FIG. 6D illustrates a system 660 including a blockchain, according toexample embodiments. Referring to the example of FIG. 6D, an applicationprogramming interface (API) gateway 662 provides a common interface foraccessing blockchain logic (e.g., smart contract 630 or other chaincode)and data (e.g., distributed ledger, etc.). In this example, the APIgateway 662 is a common interface for performing transactions (invoke,queries, etc.) on the blockchain by connecting one or more entities 652and 656 to a blockchain peer (i.e., server 654). Here, the server 654 isa blockchain network peer component that holds a copy of the world stateand a distributed ledger allowing clients 652 and 656 to query data onthe world state as well as submit transactions into the blockchainnetwork where, depending on the smart contract 630 and endorsementpolicy, endorsing peers will run the smart contracts 630.

The above embodiments may be implemented in hardware, in a computerprogram executed by a processor, in firmware, or in a combination of theabove. A computer program may be embodied on a computer readable medium,such as a storage medium. For example, a computer program may reside inrandom access memory (“RAM”), flash memory, read-only memory (“ROM”),erasable programmable read-only memory (“EPROM”), electrically erasableprogrammable read-only memory (“EEPROM”), registers, hard disk, aremovable disk, a compact disk read-only memory (“CD-ROM”), or any otherform of storage medium known in the art.

An exemplary storage medium may be coupled to the processor such thatthe processor may read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor. The processor and the storage medium may reside in anapplication specific integrated circuit (“ASIC”). In the alternative,the processor and the storage medium may reside as discrete components.

FIG. 7A illustrates a process 700 of a new block being added to adistributed ledger 720, according to example embodiments, and FIG. 7Billustrates contents of a new data block structure 730 for blockchain,according to example embodiments. Referring to FIG. 7A, clients (notshown) may submit transactions to blockchain nodes 711, 712, and/or 713.Clients may be instructions received from any source to enact activityon the blockchain 720. As an example, clients may be applications thatact on behalf of a requester, such as a device, person or entity topropose transactions for the blockchain. The plurality of blockchainpeers (e.g., blockchain nodes 711, 712, and 713) may maintain a state ofthe blockchain network and a copy of the distributed ledger 720.Different types of blockchain nodes/peers may be present in theblockchain network including endorsing peers which simulate and endorsetransactions proposed by clients and committing peers which verifyendorsements, validate transactions, and commit transactions to thedistributed ledger 720. In this example, the blockchain nodes 711, 712,and 713 may perform the role of endorser node, committer node, or both.

The distributed ledger 720 includes a blockchain which stores immutable,sequenced records in blocks, and a state database 724 (current worldstate) maintaining a current state of the blockchain 722. Onedistributed ledger 720 may exist per channel and each peer maintains itsown copy of the distributed ledger 720 for each channel of which theyare a member. The blockchain 722 is a transaction log, structured ashash-linked blocks where each block contains a sequence of Ntransactions. Blocks may include various components such as shown inFIG. 7B. The linking of the blocks (shown by arrows in FIG. 7A) may begenerated by adding a hash of a prior block's header within a blockheader of a current block. In this way, all transactions on theblockchain 722 are sequenced and cryptographically linked togetherpreventing tampering with blockchain data without breaking the hashlinks. Furthermore, because of the links, the latest block in theblockchain 722 represents every transaction that has come before it. Theblockchain 722 may be stored on a peer file system (local or attachedstorage), which supports an append-only blockchain workload.

The current state of the blockchain 722 and the distributed ledger 722may be stored in the state database 724. Here, the current state datarepresents the latest values for all keys ever included in the chaintransaction log of the blockchain 722. Chaincode invocations executetransactions against the current state in the state database 724. Tomake these chaincode interactions extremely efficient, the latest valuesof all keys are stored in the state database 724. The state database 724may include an indexed view into the transaction log of the blockchain722, it can therefore be regenerated from the chain at any time. Thestate database 724 may automatically get recovered (or generated ifneeded) upon peer startup, before transactions are accepted.

Endorsing nodes receive transactions from clients and endorse thetransaction based on simulated results. Endorsing nodes hold smartcontracts which simulate the transaction proposals. When an endorsingnode endorses a transaction, the endorsing nodes creates a transactionendorsement which is a signed response from the endorsing node to theclient application indicating the endorsement of the simulatedtransaction. The method of endorsing a transaction depends on anendorsement policy which may be specified within chaincode. An exampleof an endorsement policy is “the majority of endorsing peers mustendorse the transaction”. Different channels may have differentendorsement policies. Endorsed transactions are forward by the clientapplication to ordering service 710.

The ordering service 710 accepts endorsed transactions, orders them intoa block, and delivers the blocks to the committing peers. For example,the ordering service 710 may initiate a new block when a threshold oftransactions has been reached, a timer times out, or another condition.In the example of FIG. 7A, blockchain node 712 is a committing peer thathas received a new data new data block 730 for storage on blockchain720. The first block in the blockchain may be referred to as a genesisblock which includes information about the blockchain, its members, thedata stored therein, etc.

The ordering service 710 may be made up of a cluster of orderers. Theordering service 710 does not process transactions, smart contracts, ormaintain the shared ledger. Rather, the ordering service 710 may acceptthe endorsed transactions and specifies the order in which thosetransactions are committed to the distributed ledger 720. Thearchitecture of the blockchain network may be designed such that thespecific implementation of ‘ordering’ (e.g., Solo, Kafka, BFT, etc.)becomes a pluggable component.

Transactions are written to the distributed ledger 720 in a consistentorder. The order of transactions is established to ensure that theupdates to the state database 724 are valid when they are committed tothe network. Unlike a cryptocurrency blockchain system (e.g., Bitcoin,etc.) where ordering occurs through the solving of a cryptographicpuzzle, or mining, in this example the parties of the distributed ledger720 may choose the ordering mechanism that best suits that network.

When the ordering service 710 initializes a new data block 730, the newdata block 730 may be broadcast to committing peers (e.g., blockchainnodes 711, 712, and 713). In response, each committing peer validatesthe transaction within the new data block 730 by checking to make surethat the read set and the write set still match the current world statein the state database 724. Specifically, the committing peer candetermine whether the read data that existed when the endorserssimulated the transaction is identical to the current world state in thestate database 724. When the committing peer validates the transaction,the transaction is written to the blockchain 722 on the distributedledger 720, and the state database 724 is updated with the write datafrom the read-write set. If a transaction fails, that is, if thecommitting peer finds that the read-write set does not match the currentworld state in the state database 724, the transaction ordered into ablock will still be included in that block, but it will be marked asinvalid, and the state database 724 will not be updated.

Referring to FIG. 7B, a new data block 730 (also referred to as a datablock) that is stored on the blockchain 722 of the distributed ledger720 may include multiple data segments such as a block header 740, blockdata 750, and block metadata 760. It should be appreciated that thevarious depicted blocks and their contents, such as new data block 730and its contents. Shown in FIG. 7B are merely examples and are not meantto limit the scope of the example embodiments. The new data block 730may store transactional information of N transaction(s) (e.g., 1, 10,100, 500, 1000, 2000, 3000, etc.) within the block data 750. The newdata block 730 may also include a link to a previous block (e.g., on theblockchain 722 in FIG. 7A) within the block header 740. In particular,the block header 740 may include a hash of a previous block's header.The block header 740 may also include a unique block number, a hash ofthe block data 750 of the new data block 730, and the like. The blocknumber of the new data block 730 may be unique and assigned in variousorders, such as an incremental/sequential order starting from zero.

The block data 750 may store transactional information of eachtransaction that is recorded within the new data block 730. For example,the transaction data may include one or more of a type of thetransaction, a version, a timestamp, a channel ID of the distributedledger 720, a transaction ID, an epoch, a payload visibility, achaincode path (deploy tx), a chaincode name, a chaincode version, input(chaincode and functions), a client (creator) identify such as a publickey and certificate, a signature of the client, identities of endorsers,endorser signatures, a proposal hash, chaincode events, response status,namespace, a read set (list of key and version read by the transaction,etc.), a write set (list of key and value, etc.), a start key, an endkey, a list of keys, a Merkel tree query summary, and the like. Thetransaction data may be stored for each of the N transactions.

In some embodiments, the block data 750 may also store new data 762which adds additional information to the hash-linked chain of blocks inthe blockchain 722. The additional information includes one or more ofthe steps, features, processes and/or actions described or depictedherein. Accordingly, the new data 762 can be stored in an immutable logof blocks on the distributed ledger 720. Some of the benefits of storingsuch new data 762 are reflected in the various embodiments disclosed anddepicted herein. Although in FIG. 7B the new data 762 is depicted in theblock data 750 but could also be located in the block header 740 or theblock metadata 760.

The block metadata 760 may store multiple fields of metadata (e.g., as abyte array, etc.). Metadata fields may include signature on blockcreation, a reference to a last configuration block, a transactionfilter identifying valid and invalid transactions within the block, lastoffset persisted of an ordering service that ordered the block, and thelike. The signature, the last configuration block, and the orderermetadata may be added by the ordering service 710. Meanwhile, acommitter of the block (such as blockchain node 712) may addvalidity/invalidity information based on an endorsement policy,verification of read/write sets, and the like. The transaction filtermay include a byte array of a size equal to the number of transactionsin the block data 750 and a validation code identifying whether atransaction was valid/invalid.

FIG. 7C illustrates an embodiment of a blockchain 770 for digitalcontent in accordance with the embodiments described herein. The digitalcontent may include one or more files and associated information. Thefiles may include media, images, video, audio, text, links, graphics,animations, web pages, documents, or other forms of digital content. Theimmutable, append-only aspects of the blockchain serve as a safeguard toprotect the integrity, validity, and authenticity of the digitalcontent, making it suitable use in legal proceedings where admissibilityrules apply or other settings where evidence is taken in toconsideration or where the presentation and use of digital informationis otherwise of interest. In this case, the digital content may bereferred to as digital evidence.

The blockchain may be formed in various ways. In one embodiment, thedigital content may be included in and accessed from the blockchainitself. For example, each block of the blockchain may store a hash valueof reference information (e.g., header, value, etc.) along theassociated digital content. The hash value and associated digitalcontent may then be encrypted together. Thus, the digital content ofeach block may be accessed by decrypting each block in the blockchain,and the hash value of each block may be used as a basis to reference aprevious block. This may be illustrated as follows:

Block 1 Block 2 . . . Block N Hash Value 1 Hash Value 2 Hash Value NDigital Content 1 Digital Content 2 Digital Content N

In one embodiment, the digital content may be not included in theblockchain. For example, the blockchain may store the encrypted hashesof the content of each block without any of the digital content. Thedigital content may be stored in another storage area or memory addressin association with the hash value of the original file. The otherstorage area may be the same storage device used to store the blockchainor may be a different storage area or even a separate relationaldatabase. The digital content of each block may be referenced oraccessed by obtaining or querying the hash value of a block of interestand then looking up that has value in the storage area, which is storedin correspondence with the actual digital content. This operation may beperformed, for example, a database gatekeeper. This may be illustratedas follows:

Blockchain Storage Area Block 1 Hash Value Block 1 Hash Value . . .Content . . . . . . Block N Hash Value Block N Hash Value . . . Content

In the example embodiment of FIG. 7C, the blockchain 770 includes anumber of blocks 778 ₁, 778 ₂, . . . 778 _(N) cryptographically linkedin an ordered sequence, where N≥1. The encryption used to link theblocks 778 ₁, 778 ₂, . . . 778 _(N) may be any of a number of keyed orun-keyed Hash functions. In one embodiment, the blocks 778 ₁, 778 ₂, . .. 778 _(N) are subject to a hash function which produces n-bitalphanumeric outputs (where n is 256 or another number) from inputs thatare based on information in the blocks. Examples of such a hash functioninclude, but are not limited to, a SHA-type (SHA stands for Secured HashAlgorithm) algorithm, Merkle-Damgard algorithm, HAIFA algorithm,Merkle-tree algorithm, nonce-based algorithm, and anon-collision-resistant PRF algorithm. In another embodiment, the blocks778 ₁, 778 ₂, . . . 778 _(N) may be cryptographically linked by afunction that is different from a hash function. For purposes ofillustration, the following description is made with reference to a hashfunction, e.g., SHA-2.

Each of the blocks 778 ₁, 778 ₂, . . . 778 _(N) in the blockchainincludes a header, a version of the file, and a value. The header andthe value are different for each block as a result of hashing in theblockchain. In one embodiment, the value may be included in the header.As described in greater detail below, the version of the file may be theoriginal file or a different version of the original file.

The first block 778 ₁ in the blockchain is referred to as the genesisblock and includes the header 772 ₁, original file 774 ₁, and an initialvalue 776 ₁. The hashing scheme used for the genesis block, and indeedin all subsequent blocks, may vary. For example, all the information inthe first block 778 ₁ may be hashed together and at one time, or each ora portion of the information in the first block 778 ₁ may be separatelyhashed and then a hash of the separately hashed portions may beperformed.

The header 772 ₁ may include one or more initial parameters, which, forexample, may include a version number, timestamp, nonce, rootinformation, difficulty level, consensus protocol, duration, mediaformat, source, descriptive keywords, and/or other informationassociated with original file 774 ₁ and/or the blockchain. The header772 ₁ may be generated automatically (e.g., by blockchain networkmanaging software) or manually by a blockchain participant. Unlike theheader in other blocks 778 ₂ to 778 _(N) in the blockchain, the header772 ₁ in the genesis block does not reference a previous block, simplybecause there is no previous block.

The original file 774 ₁ in the genesis block may be, for example, dataas captured by a device with or without processing prior to itsinclusion in the blockchain. The original file 774 ₁ is received throughthe interface of the system from the device, media source, or node. Theoriginal file 774 ₁ is associated with metadata, which, for example, maybe generated by a user, the device, and/or the system processor, eithermanually or automatically. The metadata may be included in the firstblock 778 ₁ in association with the original file 774 ₁.

The value 776 ₁ in the genesis block is an initial value generated basedon one or more unique attributes of the original file 774 ₁. In oneembodiment, the one or more unique attributes may include the hash valuefor the original file 774 ₁, metadata for the original file 774 ₁, andother information associated with the file. In one implementation, theinitial value 776 ₁ may be based on the following unique attributes:

-   -   1) SHA-2 computed hash value for the original file    -   2) originating device ID    -   3) starting timestamp for the original file    -   4) initial storage location of the original file    -   5) blockchain network member ID for software to currently        control the original file and associated metadata

The other blocks 778 ₂ to 778 _(N) in the blockchain also have headers,files, and values. However, unlike the first block 772 ₁, each of theheaders 772 ₂ to 772 _(N) in the other blocks includes the hash value ofan immediately preceding block. The hash value of the immediatelypreceding block may be just the hash of the header of the previous blockor may be the hash value of the entire previous block. By including thehash value of a preceding block in each of the remaining blocks, a tracecan be performed from the Nth block back to the genesis block (and theassociated original file) on a block-by-block basis, as indicated byarrows 780, to establish an auditable and immutable chain-of-custody.

Each of the header 772 ₂ to 772 _(N) in the other blocks may alsoinclude other information, e.g., version number, timestamp, nonce, rootinformation, difficulty level, consensus protocol, and/or otherparameters or information associated with the corresponding files and/orthe blockchain in general.

The files 774 ₂ to 774 _(N) in the other blocks may be equal to theoriginal file or may be a modified version of the original file in thegenesis block depending, for example, on the type of processingperformed. The type of processing performed may vary from block toblock. The processing may involve, for example, any modification of afile in a preceding block, such as redacting information or otherwisechanging the content of, taking information away from, or adding orappending information to the files.

Additionally, or alternatively, the processing may involve merelycopying the file from a preceding block, changing a storage location ofthe file, analyzing the file from one or more preceding blocks, movingthe file from one storage or memory location to another, or performingaction relative to the file of the blockchain and/or its associatedmetadata. Processing which involves analyzing a file may include, forexample, appending, including, or otherwise associating variousanalytics, statistics, or other information associated with the file.

The values in each of the other blocks 776 ₂ to 776 _(N) in the otherblocks are unique values and are all different as a result of theprocessing performed. For example, the value in any one blockcorresponds to an updated version of the value in the previous block.The update is reflected in the hash of the block to which the value isassigned. The values of the blocks therefore provide an indication ofwhat processing was performed in the blocks and also permit a tracingthrough the blockchain back to the original file. This tracking confirmsthe chain-of-custody of the file throughout the entire blockchain.

For example, consider the case where portions of the file in a previousblock are redacted, blocked out, or pixelated in order to protect theidentity of a person shown in the file. In this case, the blockincluding the redacted file will include metadata associated with theredacted file, e.g., how the redaction was performed, who performed theredaction, timestamps where the redaction(s) occurred, etc. The metadatamay be hashed to form the value. Because the metadata for the block isdifferent from the information that was hashed to form the value in theprevious block, the values are different from one another and may berecovered when decrypted.

In one embodiment, the value of a previous block may be updated (e.g., anew hash value computed) to form the value of a current block when anyone or more of the following occurs. The new hash value may be computedby hashing all or a portion of the information noted below, in thisexample embodiment.

-   -   a) new SHA-2 computed hash value if the file has been processed        in any way (e.g., if the file was redacted, copied, altered,        accessed, or some other action was taken)    -   b) new storage location for the file    -   c) new metadata identified associated with the file    -   d) transfer of access or control of the file from one blockchain        participant to another blockchain participant

FIG. 7D illustrates an embodiment of a block which may represent thestructure of the blocks in the blockchain 790 in accordance with oneembodiment. The block, Block_(i), includes a header 772 _(i), a file 774_(i), and a value 776 _(i).

The header 772 _(i) includes a hash value of a previous blockBlock_(i-1) and additional reference information, which, for example,may be any of the types of information (e.g., header informationincluding references, characteristics, parameters, etc.) discussedherein. All blocks reference the hash of a previous block except, ofcourse, the genesis block. The hash value of the previous block may bejust a hash of the header in the previous block or a hash of all or aportion of the information in the previous block, including the file andmetadata.

The file 774 _(i) includes a plurality of data, such as Data 1, Data 2,. . . , Data N in sequence. The data are tagged with metadata Metadata1, Metadata 2, . . . , Metadata N which describe the content and/orcharacteristics associated with the data. For example, the metadata foreach data may include information to indicate a timestamp for the data,process the data, keywords indicating the persons or other contentdepicted in the data, and/or other features that may be helpful toestablish the validity and content of the file as a whole, andparticularly its use a digital evidence, for example, as described inconnection with an embodiment discussed below. In addition to themetadata, each data may be tagged with reference REF₁, REF₂, . . . ,REF_(N) to a previous data to prevent tampering, gaps in the file, andsequential reference through the file.

Once the metadata is assigned to the data (e.g., through a smartcontract), the metadata cannot be altered without the hash changing,which can easily be identified for invalidation. The metadata, thus,creates a data log of information that may be accessed for use byparticipants in the blockchain.

The value 776 _(i) is a hash value or other value computed based on anyof the types of information previously discussed. For example, for anygiven block Block_(i), the value for that block may be updated toreflect the processing that was performed for that block, e.g., new hashvalue, new storage location, new metadata for the associated file,transfer of control or access, identifier, or other action orinformation to be added. Although the value in each block is shown to beseparate from the metadata for the data of the file and header, thevalue may be based, in part or whole, on this metadata in anotherembodiment.

Once the blockchain 770 is formed, at any point in time, the immutablechain-of-custody for the file may be obtained by querying the blockchainfor the transaction history of the values across the blocks. This query,or tracking procedure, may begin with decrypting the value of the blockthat is most currently included (e.g., the last (N^(th)) block), andthen continuing to decrypt the value of the other blocks until thegenesis block is reached and the original file is recovered. Thedecryption may involve decrypting the headers and files and associatedmetadata at each block, as well.

Decryption is performed based on the type of encryption that took placein each block. This may involve the use of private keys, public keys, ora public key-private key pair. For example, when asymmetric encryptionis used, blockchain participants or a processor in the network maygenerate a public key and private key pair using a predeterminedalgorithm. The public key and private key are associated with each otherthrough some mathematical relationship. The public key may bedistributed publicly to serve as an address to receive messages fromother users, e.g., an IP address or home address. The private key iskept secret and used to digitally sign messages sent to other blockchainparticipants. The signature is included in the message so that therecipient can verify using the public key of the sender. This way, therecipient can be sure that only the sender could have sent this message.

Generating a key pair may be analogous to creating an account on theblockchain, but without having to actually register anywhere. Also,every transaction that is executed on the blockchain is digitally signedby the sender using their private key. This signature ensures that onlythe owner of the account can track and process (if within the scope ofpermission determined by a smart contract) the file of the blockchain.

FIG. 8 illustrates an example system 800 that supports one or more ofthe example embodiments described and/or depicted herein. The system 800comprises a computer system/server 802, which is operational withnumerous other general purpose or special purpose computing systemenvironments or configurations. Examples of well-known computingsystems, environments, and/or configurations that may be suitable foruse with computer system/server 802 include, but are not limited to,personal computer systems, server computer systems, thin clients, thickclients, hand-held or laptop devices, multiprocessor systems,microprocessor-based systems, set top boxes, programmable consumerelectronics, network PCs, minicomputer systems, mainframe computersystems, and distributed cloud computing environments that include anyof the above systems or devices, and the like.

Computer system/server 802 may be described in the general context ofcomputer system-executable instructions, such as program modules, beingexecuted by a computer system. Generally, program modules may includeroutines, programs, objects, components, logic, data structures, and soon that perform particular tasks or implement particular abstract datatypes. Computer system/server 802 may be practiced in distributed cloudcomputing environments where tasks are performed by remote processingdevices that are linked through a communications network. In adistributed cloud computing environment, program modules may be locatedin both local and remote computer system storage media including memorystorage devices.

As shown in FIG. 8, computer system/server 802 in cloud computing node800 is shown in the form of a general-purpose computing device. Thecomponents of computer system/server 802 may include, but are notlimited to, one or more processors or processing units 804, a systemmemory 806, and a bus that couples various system components includingsystem memory 806 to processor 804.

The bus represents one or more of any of several types of busstructures, including a memory bus or memory controller, a peripheralbus, an accelerated graphics port, and a processor or local bus usingany of a variety of bus architectures. By way of example, and notlimitation, such architectures include Industry Standard Architecture(ISA) bus, Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA)bus, Video Electronics Standards Association (VESA) local bus, andPeripheral Component Interconnects (PCI) bus.

Computer system/server 802 typically includes a variety of computersystem readable media. Such media may be any available media that isaccessible by computer system/server 802, and it includes both volatileand non-volatile media, removable and non-removable media. System memory806, in one embodiment, implements the flow diagrams of the otherfigures. The system memory 806 can include computer system readablemedia in the form of volatile memory, such as random-access memory (RAM)810 and/or cache memory 812. Computer system/server 802 may furtherinclude other removable/non-removable, volatile/non-volatile computersystem storage media. By way of example only, storage system 814 can beprovided for reading from and writing to a non-removable, non-volatilemagnetic media (not shown and typically called a “hard drive”). Althoughnot shown, a magnetic disk drive for reading from and writing to aremovable, non-volatile magnetic disk (e.g., a “floppy disk”), and anoptical disk drive for reading from or writing to a removable,non-volatile optical disk such as a CD-ROM, DVD-ROM or other opticalmedia can be provided. In such instances, each can be connected to thebus by one or more data media interfaces. As will be further depictedand described below, memory 806 may include at least one program producthaving a set (e.g., at least one) of program modules that are configuredto carry out the functions of various embodiments of the application.

Program/utility 816, having a set (at least one) of program modules 818,may be stored in memory 806 by way of example, and not limitation, aswell as an operating system, one or more application programs, otherprogram modules, and program data. Each of the operating system, one ormore application programs, other program modules, and program data orsome combination thereof, may include an implementation of a networkingenvironment. Program modules 818 generally carry out the functionsand/or methodologies of various embodiments of the application asdescribed herein.

As will be appreciated by one skilled in the art, aspects of the presentapplication may be embodied as a system, method, or computer programproduct. Accordingly, aspects of the present application may take theform of an entirely hardware embodiment, an entirely software embodiment(including firmware, resident software, micro-code, etc.) or anembodiment combining software and hardware aspects that may allgenerally be referred to herein as a “circuit,” “module” or “system.”Furthermore, aspects of the present application may take the form of acomputer program product embodied in one or more computer readablemedium(s) having computer readable program code embodied thereon.

Computer system/server 802 may also communicate with one or moreexternal devices 820 such as a keyboard, a pointing device, a display822, etc.; one or more devices that enable a user to interact withcomputer system/server 802; and/or any devices (e.g., network card,modem, etc.) that enable computer system/server 802 to communicate withone or more other computing devices. Such communication can occur viaI/O interfaces 824. Still yet, computer system/server 802 cancommunicate with one or more networks such as a local area network(LAN), a general wide area network (WAN), and/or a public network (e.g.,the Internet) via network adapter 826. As depicted, network adapter 826communicates with the other components of computer system/server 802 viaa bus. It should be understood that although not shown, other hardwareand/or software components could be used in conjunction with computersystem/server 802. Examples, include, but are not limited to: microcode,device drivers, redundant processing units, external disk drive arrays,RAID systems, tape drives, and data archival storage systems, etc.

Although an exemplary embodiment of at least one of a system, method,and non-transitory computer readable medium has been illustrated in theaccompanied drawings and described in the foregoing detaileddescription, it will be understood that the application is not limitedto the embodiments disclosed, but is capable of numerous rearrangements,modifications, and substitutions as set forth and defined by thefollowing claims. For example, the capabilities of the system of thevarious figures can be performed by one or more of the modules orcomponents described herein or in a distributed architecture and mayinclude a transmitter, receiver or pair of both. For example, all orpart of the functionality performed by the individual modules, may beperformed by one or more of these modules. Further, the functionalitydescribed herein may be performed at various times and in relation tovarious events, internal or external to the modules or components. Also,the information sent between various modules can be sent between themodules via at least one of: a data network, the Internet, a voicenetwork, an Internet Protocol network, a wireless device, a wired deviceand/or via plurality of protocols. Also, the messages sent or receivedby any of the modules may be sent or received directly and/or via one ormore of the other modules.

One skilled in the art will appreciate that a “system” could be embodiedas a personal computer, a server, a console, a personal digitalassistant (PDA), a cell phone, a tablet computing device, a smartphoneor any other suitable computing device, or combination of devices.Presenting the above-described functions as being performed by a“system” is not intended to limit the scope of the present applicationin any way but is intended to provide one example of many embodiments.Indeed, methods, systems and apparatuses disclosed herein may beimplemented in localized and distributed forms consistent with computingtechnology.

It should be noted that some of the system features described in thisspecification have been presented as modules, in order to moreparticularly emphasize their implementation independence. For example, amodule may be implemented as a hardware circuit comprising custom verylarge-scale integration (VLSI) circuits or gate arrays, off-the-shelfsemiconductors such as logic chips, transistors, or other discretecomponents. A module may also be implemented in programmable hardwaredevices such as field programmable gate arrays, programmable arraylogic, programmable logic devices, graphics processing units, or thelike.

A module may also be at least partially implemented in software forexecution by various types of processors. An identified unit ofexecutable code may, for instance, comprise one or more physical orlogical blocks of computer instructions that may, for instance, beorganized as an object, procedure, or function. Nevertheless, theexecutables of an identified module need not be physically locatedtogether but may comprise disparate instructions stored in differentlocations which, when joined logically together, comprise the module andachieve the stated purpose for the module. Further, modules may bestored on a computer-readable medium, which may be, for instance, a harddisk drive, flash device, random access memory (RAM), tape, or any othersuch medium used to store data.

Indeed, a module of executable code could be a single instruction, ormany instructions, and may even be distributed over several differentcode segments, among different programs, and across several memorydevices. Similarly, operational data may be identified and illustratedherein within modules and may be embodied in any suitable form andorganized within any suitable type of data structure. The operationaldata may be collected as a single data set or may be distributed overdifferent locations including over different storage devices, and mayexist, at least partially, merely as electronic signals on a system ornetwork.

It will be readily understood that the components of the application, asgenerally described and illustrated in the figures herein, may bearranged and designed in a wide variety of different configurations.Thus, the detailed description of the embodiments is not intended tolimit the scope of the application as claimed but is merelyrepresentative of selected embodiments of the application.

One having ordinary skill in the art will readily understand that theabove may be practiced with steps in a different order, and/or withhardware elements in configurations that are different than those whichare disclosed. Therefore, although the application has been describedbased upon these preferred embodiments, it would be apparent to those ofskill in the art that certain modifications, variations, and alternativeconstructions would be apparent.

While preferred embodiments of the present application have beendescribed, it is to be understood that the embodiments described areillustrative only and the scope of the application is to be definedsolely by the appended claims when considered with a full range ofequivalents and modifications (e.g., protocols, hardware devices,software platforms etc.) thereto.

What is claimed is:
 1. A first blockchain client in a blockchain network comprising a plurality of blockchain nodes and a second blockchain client, the first blockchain client comprising: a memory storing one or more instructions; and a processor that when executing the one or more instructions configures the processor to: generate and send a transaction to the plurality of blockchain nodes requesting to transfer a document to the second blockchain client, receive a first key from the second blockchain client via a private channel between the first blockchain client and the second blockchain client in response to the plurality of blockchain nodes endorsing the transaction, encrypt the document using a shared key, transfer the encrypted document to the second blockchain client via the private channel, receive an endorsed acknowledgment transaction from the plurality of blockchain nodes in response to the plurality of blockchain nodes receiving an acknowledgment transaction acknowledging receipt of the document from the second blockchain client, send the shared key encrypted with the first key to one of: the second blockchain client, or the plurality of blockchain nodes; and receive an endorsed encrypted key transaction from the plurality of blockchain nodes.
 2. The first blockchain client of claim 1, wherein the acknowledgment transaction comprises a hash of the encrypted document calculated by the second blockchain client.
 3. The first blockchain client of claim 2, wherein, when the processor is configured to send the shared key encrypted with the first key to the plurality of blockchain nodes, the processor is further configured to: generate and send an encrypted key transaction comprising the shared key encrypted with the first key to the plurality of blockchain nodes.
 4. The first blockchain client of claim 2, wherein, when the processor is configured to send the shared key encrypted with the first key to the second blockchain client, the processor is further configured to: send the shared key encrypted with the first key to the second blockchain client via the private channel.
 5. The system of claim 1, wherein, when the processor is configured to receive an endorsed encrypted key transaction from the plurality of blockchain nodes, the processor is further configured to: receive the endorsed encrypted key transaction from the plurality of blockchain nodes generated based on a second acknowledgement received by the plurality of blockchain nodes from the second blockchain client.
 6. The first blockchain client of claim 5, wherein the second acknowledgement comprises a hash of the shared key encrypted with the first key.
 7. The first blockchain client of claim 1, wherein all transactions are recorded to a shared ledger of the blockchain network and provide information to resolve a dispute or a theft of personal information.
 8. A method, comprising: generating, by a first blockchain client in a blockchain network comprising a plurality of blockchain nodes and a second blockchain client, a transaction to the plurality of blockchain nodes requesting to transfer a document to the second blockchain client; receiving, by the first blockchain client, a first key from the second blockchain client via a private channel between the first blockchain client and the second blockchain client in response to the plurality of blockchain nodes endorsing the transaction; encrypting, by the first blockchain client, the document using a shared key; transferring, by the first blockchain client, the encrypted document to the second blockchain client via the private channel; receiving, by the first blockchain client, an endorsed acknowledgment transaction from the plurality of blockchain nodes in response to the plurality of blockchain nodes receiving an acknowledgment transaction acknowledging receipt of the document from the second blockchain client; sending, by the first blockchain client, the shared key encrypted with the first key to one of: the second blockchain client, or the plurality of blockchain nodes; and receiving, by the first blockchain client, an endorsed encrypted key transaction from the plurality of blockchain nodes.
 9. The method of claim 8, wherein the acknowledgment transaction comprises a hash of the encrypted document calculated by the second blockchain client.
 10. The method of claim 9, wherein the sending the shared key encrypted with the first key to the plurality of blockchain nodes further comprises: generating and sending, by the first blockchain client, an encrypted key transaction comprising the shared key encrypted with the first key to the plurality of blockchain nodes.
 11. The method of claim 9, wherein the sending the shared key encrypted with the first key to the second blockchain client further comprises: sending, by the first blockchain client, the shared key encrypted with the first key to the second blockchain client via the private channel.
 12. The method of claim 8, wherein the receiving an endorsed encrypted key transaction from the plurality of blockchain nodes further comprises: receiving, by the first blockchain client, the endorsed encrypted key transaction from the plurality of blockchain nodes generated based on a second acknowledgement received by the plurality of blockchain nodes from the second blockchain client.
 13. The method of claim 12, wherein the second acknowledgement comprises a hash of the shared key encrypted with the first key.
 14. The method of claim 8, wherein all transactions are recorded to a shared ledger of the blockchain network and provide information to resolve a dispute or a theft of personal information.
 15. A non-transitory computer readable medium comprising one or more instructions that when executed by a processor of a first blockchain client in a blockchain network comprising a plurality of blockchain nodes and a second blockchain client cause the processor to perform: generating a transaction to the plurality of blockchain nodes requesting to transfer a document to the second blockchain client; receiving a first key from the second blockchain client via a private channel between the first blockchain client and the second blockchain client in response to the plurality of blockchain nodes endorsing the transaction; encrypting the document using a shared key; transferring the encrypted document to the second blockchain client via the private channel; receiving an endorsed acknowledgment transaction from the plurality of blockchain nodes in response to the plurality of blockchain nodes receiving an acknowledgment transaction acknowledging receipt of the document from the second blockchain client; sending the shared key encrypted with the first key to one of: the second blockchain client, or the plurality of blockchain nodes; and receiving an endorsed encrypted key transaction from the plurality of blockchain nodes.
 16. The non-transitory computer readable medium of claim 15, wherein the acknowledgment transaction comprises a hash of the encrypted document.
 17. The non-transitory computer readable medium of claim 16, wherein the sending the shared key encrypted with the first key to the plurality of blockchain nodes further comprises: generating and sending an encrypted key transaction comprising the shared key encrypted with the first key to the plurality of blockchain nodes.
 18. The non-transitory computer readable medium of claim 16, wherein the sending the shared key encrypted with the first key to the second blockchain client further comprises: sending the shared key encrypted with the first key to the second blockchain client via the private channel.
 19. The non-transitory computer readable medium of claim 15, wherein the receiving an endorsed encrypted key transaction from the plurality of blockchain nodes further comprises: receiving the endorsed encrypted key transaction from the plurality of blockchain nodes generated based on a second acknowledgement received by the plurality of blockchain nodes from the second blockchain client.
 20. The non-transitory computer readable medium of claim 19, wherein the second acknowledgement comprises a hash of the shared key encrypted with the first key. 